In electric vehicle (EV)/fuel cell electric vehicle (FCEV)/hybrid electric vehicle (HEV) propulsion applications, one concern is with maintaining the vehicle battery within a predetermined range of operating voltage and power. When the battery operates beyond the predetermined range, this operation may lead to a reduced life span of the battery or otherwise negatively impact the performance of the battery. A number of different vehicle systems and functions draw current and power from the battery. For example, during motoring, the traction system typically draws current and power from the battery. In the event the traction system draws too much current, the battery voltage may drop below a minimum operating voltage of the battery.
One method of maintaining the battery within the predetermined operating range is to limit torque in the traction system. For example, during motoring, the motoring torque may be limited to keep the battery voltage above the minimum operating voltage. In another example, during a regenerating operation of the battery, the regenerating torque may be limited to keep the battery voltage below a maximum value. Open-loop torque limit tables, based on the modeling of the battery, may be used to limit torque. Because the battery model may significantly vary with respect temperature, state of charge, battery lifetime, and the like, these torque limit tables typically include margins to sufficiently account for the greatest variations which may decrease optimal operation.
Accordingly, it is desirable to provide a system for more optimally controlling electric traction drive systems. Additionally, it is desirable to provide a method for more optimally controlling electric traction drive systems. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.